[ViewVC] Diff of: cvs/Coro/Coro.pm

Comparing Coro/Coro.pm (file contents):
Revision 1.186 by root, Sun May 25 01:32:36 2008 UTC vs.
Revision 1.252 by root, Thu Apr 16 20:07:21 2009 UTC

…		…
1	=head1 NAME	1	=head1 NAME
2		2
3	Coro - coroutine process abstraction	3	Coro - the only real threads in perl
4		4
5	=head1 SYNOPSIS	5	=head1 SYNOPSIS
6		6
7	use Coro;	7	use Coro;
8		8
11	print "2\n";	11	print "2\n";
12	cede; # yield back to main	12	cede; # yield back to main
13	print "4\n";	13	print "4\n";
14	};	14	};
15	print "1\n";	15	print "1\n";
16	cede; # yield to coroutine	16	cede; # yield to coro
17	print "3\n";	17	print "3\n";
18	cede; # and again	18	cede; # and again
19		19
20	# use locking	20	# use locking
		21	use Coro::Semaphore;
21	my $lock = new Coro::Semaphore;	22	my $lock = new Coro::Semaphore;
22	my $locked;	23	my $locked;
23		24
24	$lock->down;	25	$lock->down;
25	$locked = 1;	26	$locked = 1;
26	$lock->up;	27	$lock->up;
27		28
28	=head1 DESCRIPTION	29	=head1 DESCRIPTION
29		30
30	This module collection manages coroutines. Coroutines are similar to	31	For a tutorial-style introduction, please read the L<Coro::Intro>
31	threads but don't (in general) run in parallel at the same time even	32	manpage. This manpage mainly contains reference information.
32	on SMP machines. The specific flavor of coroutine used in this module
33	also guarantees you that it will not switch between coroutines unless
34	necessary, at easily-identified points in your program, so locking and
35	parallel access are rarely an issue, making coroutine programming much
36	safer and easier than threads programming.
37		33
38	Unlike a normal perl program, however, coroutines allow you to have	34	This module collection manages continuations in general, most often in
39	multiple running interpreters that share data, which is especially useful	35	the form of cooperative threads (also called coros, or simply "coro"
40	to code pseudo-parallel processes and for event-based programming, such as	36	in the documentation). They are similar to kernel threads but don't (in
41	multiple HTTP-GET requests running concurrently. See L<Coro::AnyEvent> to	37	general) run in parallel at the same time even on SMP machines. The
42	learn more.	38	specific flavor of thread offered by this module also guarantees you that
		39	it will not switch between threads unless necessary, at easily-identified
		40	points in your program, so locking and parallel access are rarely an
		41	issue, making thread programming much safer and easier than using other
		42	thread models.
43		43
44	Coroutines are also useful because Perl has no support for threads (the so	44	Unlike the so-called "Perl threads" (which are not actually real threads
45	called "threads" that perl offers are nothing more than the (bad) process	45	but only the windows process emulation ported to unix, and as such act
46	emulation coming from the Windows platform: On standard operating systems	46	as processes), Coro provides a full shared address space, which makes
47	they serve no purpose whatsoever, except by making your programs slow and	47	communication between threads very easy. And Coro's threads are fast,
48	making them use a lot of memory. Best disable them when building perl, or	48	too: disabling the Windows process emulation code in your perl and using
49	aks your software vendor/distributor to do it for you).	49	Coro can easily result in a two to four times speed increase for your
		50	programs. A parallel matrix multiplication benchmark runs over 300 times
		51	faster on a single core than perl's pseudo-threads on a quad core using
		52	all four cores.
50		53
		54	Coro achieves that by supporting multiple running interpreters that share
		55	data, which is especially useful to code pseudo-parallel processes and
		56	for event-based programming, such as multiple HTTP-GET requests running
		57	concurrently. See L<Coro::AnyEvent> to learn more on how to integrate Coro
		58	into an event-based environment.
		59
51	In this module, coroutines are defined as "callchain + lexical variables +	60	In this module, a thread is defined as "callchain + lexical variables +
52	@_ + $_ + $@ + $/ + C stack), that is, a coroutine has its own callchain,	61	some package variables + C stack), that is, a thread has its own callchain,
53	its own set of lexicals and its own set of perls most important global	62	its own set of lexicals and its own set of perls most important global
54	variables (see L<Coro::State> for more configuration).	63	variables (see L<Coro::State> for more configuration and background info).
		64
		65	See also the C<SEE ALSO> section at the end of this document - the Coro
		66	module family is quite large.
55		67
56	=cut	68	=cut
57		69
58	package Coro;	70	package Coro;
59		71
60	use strict;	72	use strict qw(vars subs);
61	no warnings "uninitialized";	73	no warnings "uninitialized";
62		74
		75	use Guard ();
		76
63	use Coro::State;	77	use Coro::State;
64		78
65	use base qw(Coro::State Exporter);	79	use base qw(Coro::State Exporter);
66		80
67	our $idle; # idle handler	81	our $idle; # idle handler
68	our $main; # main coroutine	82	our $main; # main coro
69	our $current; # current coroutine	83	our $current; # current coro
70		84
71	our $VERSION = '4.72';	85	our $VERSION = 5.131;
72		86
73	our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub);	87	our @EXPORT = qw(async async_pool cede schedule terminate current unblock_sub);
74	our %EXPORT_TAGS = (	88	our %EXPORT_TAGS = (
75	prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],	89	prio => [qw(PRIO_MAX PRIO_HIGH PRIO_NORMAL PRIO_LOW PRIO_IDLE PRIO_MIN)],
76	);	90	);
77	our @EXPORT_OK = (@{$EXPORT_TAGS{prio}}, qw(nready));	91	our @EXPORT_OK = (@{$EXPORT_TAGS{prio}}, qw(nready));
78		92
		93	=head1 GLOBAL VARIABLES
		94
79	=over 4	95	=over 4
80		96
81	=item $Coro::main	97	=item $Coro::main
82		98
83	This variable stores the coroutine object that represents the main	99	This variable stores the Coro object that represents the main
84	program. While you cna C<ready> it and do most other things you can do to	100	program. While you cna C<ready> it and do most other things you can do to
85	coroutines, it is mainly useful to compare again C<$Coro::current>, to see	101	coro, it is mainly useful to compare again C<$Coro::current>, to see
86	wether you are running in the main program or not.	102	whether you are running in the main program or not.
87		103
88	=cut	104	=cut
89		105
90	$main = new Coro;	106	# $main is now being initialised by Coro::State
91		107
92	=item $Coro::current	108	=item $Coro::current
93		109
94	The coroutine object representing the current coroutine (the last	110	The Coro object representing the current coro (the last
95	coroutine that the Coro scheduler switched to). The initial value is	111	coro that the Coro scheduler switched to). The initial value is
96	C<$main> (of course).	112	C<$Coro::main> (of course).
97		113
98	This variable is B<strictly> I<read-only>. You can take copies of the	114	This variable is B<strictly> I<read-only>. You can take copies of the
99	value stored in it and use it as any other coroutine object, but you must	115	value stored in it and use it as any other Coro object, but you must
100	not otherwise modify the variable itself.	116	not otherwise modify the variable itself.
101		117
102	=cut	118	=cut
103		119
104	$main->{desc} = "[main::]";
105
106	# maybe some other module used Coro::Specific before...
107	$main->{_specific} = $current->{_specific}
108	if $current;
109
110	_set_current $main;
111
112	sub current() { $current } # [DEPRECATED]	120	sub current() { $current } # [DEPRECATED]
113		121
114	=item $Coro::idle	122	=item $Coro::idle
115		123
116	This variable is mainly useful to integrate Coro into event loops. It is	124	This variable is mainly useful to integrate Coro into event loops. It is
117	usually better to rely on L<Coro::AnyEvent> or LC<Coro::EV>, as this is	125	usually better to rely on L<Coro::AnyEvent> or L<Coro::EV>, as this is
118	pretty low-level functionality.	126	pretty low-level functionality.
119		127
120	This variable stores a callback that is called whenever the scheduler	128	This variable stores either a Coro object or a callback.
		129
		130	If it is a callback, the it is called whenever the scheduler finds no
121	finds no ready coroutines to run. The default implementation prints	131	ready coros to run. The default implementation prints "FATAL:
122	"FATAL: deadlock detected" and exits, because the program has no other way	132	deadlock detected" and exits, because the program has no other way to
123	to continue.	133	continue.
124		134
		135	If it is a coro object, then this object will be readied (without
		136	invoking any ready hooks, however) when the scheduler finds no other ready
		137	coros to run.
		138
125	This hook is overwritten by modules such as C<Coro::Timer> and	139	This hook is overwritten by modules such as C<Coro::EV> and
126	C<Coro::AnyEvent> to wait on an external event that hopefully wake up a	140	C<Coro::AnyEvent> to wait on an external event that hopefully wake up a
127	coroutine so the scheduler can run it.	141	coro so the scheduler can run it.
128		142
129	Note that the callback I<must not>, under any circumstances, block	143	Note that the callback I<must not>, under any circumstances, block
130	the current coroutine. Normally, this is achieved by having an "idle	144	the current coro. Normally, this is achieved by having an "idle
131	coroutine" that calls the event loop and then blocks again, and then	145	coro" that calls the event loop and then blocks again, and then
132	readying that coroutine in the idle handler.	146	readying that coro in the idle handler, or by simply placing the idle
		147	coro in this variable.
133		148
134	See L<Coro::Event> or L<Coro::AnyEvent> for examples of using this	149	See L<Coro::Event> or L<Coro::AnyEvent> for examples of using this
135	technique.	150	technique.
136		151
137	Please note that if your callback recursively invokes perl (e.g. for event	152	Please note that if your callback recursively invokes perl (e.g. for event
…		…
142	$idle = sub {	157	$idle = sub {
143	require Carp;	158	require Carp;
144	Carp::croak ("FATAL: deadlock detected");	159	Carp::croak ("FATAL: deadlock detected");
145	};	160	};
146		161
147	sub _cancel {
148	my ($self) = @_;
149
150	# free coroutine data and mark as destructed
151	$self->_destroy
152	or return;
153
154	# call all destruction callbacks
155	$_->(@{$self->{_status}})
156	for @{(delete $self->{_on_destroy}) \|\| []};
157	}
158
159	# this coroutine is necessary because a coroutine	162	# this coro is necessary because a coro
160	# cannot destroy itself.	163	# cannot destroy itself.
161	my @destroy;	164	our @destroy;
162	my $manager;	165	our $manager;
163		166
164	$manager = new Coro sub {	167	$manager = new Coro sub {
165	while () {	168	while () {
166	(shift @destroy)->_cancel	169	Coro::State::cancel shift @destroy
167	while @destroy;	170	while @destroy;
168		171
169	&schedule;	172	&schedule;
170	}	173	}
171	};	174	};
172	$manager->desc ("[coro manager]");	175	$manager->{desc} = "[coro manager]";
173	$manager->prio (PRIO_MAX);	176	$manager->prio (PRIO_MAX);
174		177
175	=back	178	=back
176		179
177	=head2 SIMPLE COROUTINE CREATION	180	=head1 SIMPLE CORO CREATION
178		181
179	=over 4	182	=over 4
180		183
181	=item async { ... } [@args...]	184	=item async { ... } [@args...]
182		185
183	Create a new coroutine and return it's coroutine object (usually	186	Create a new coro and return its Coro object (usually
184	unused). The coroutine will be put into the ready queue, so	187	unused). The coro will be put into the ready queue, so
185	it will start running automatically on the next scheduler run.	188	it will start running automatically on the next scheduler run.
186		189
187	The first argument is a codeblock/closure that should be executed in the	190	The first argument is a codeblock/closure that should be executed in the
188	coroutine. When it returns argument returns the coroutine is automatically	191	coro. When it returns argument returns the coro is automatically
189	terminated.	192	terminated.
190		193
191	The remaining arguments are passed as arguments to the closure.	194	The remaining arguments are passed as arguments to the closure.
192		195
193	See the C<Coro::State::new> constructor for info about the coroutine	196	See the C<Coro::State::new> constructor for info about the coro
194	environment in which coroutines are executed.	197	environment in which coro are executed.
195		198
196	Calling C<exit> in a coroutine will do the same as calling exit outside	199	Calling C<exit> in a coro will do the same as calling exit outside
197	the coroutine. Likewise, when the coroutine dies, the program will exit,	200	the coro. Likewise, when the coro dies, the program will exit,
198	just as it would in the main program.	201	just as it would in the main program.
199		202
200	If you do not want that, you can provide a default C<die> handler, or	203	If you do not want that, you can provide a default C<die> handler, or
201	simply avoid dieing (by use of C<eval>).	204	simply avoid dieing (by use of C<eval>).
202		205
203	Example: Create a new coroutine that just prints its arguments.	206	Example: Create a new coro that just prints its arguments.
204		207
205	async {	208	async {
206	print "@_\n";	209	print "@_\n";
207	} 1,2,3,4;	210	} 1,2,3,4;
208		211
…		…
214	$coro	217	$coro
215	}	218	}
216		219
217	=item async_pool { ... } [@args...]	220	=item async_pool { ... } [@args...]
218		221
219	Similar to C<async>, but uses a coroutine pool, so you should not call	222	Similar to C<async>, but uses a coro pool, so you should not call
220	terminate or join on it (although you are allowed to), and you get a	223	terminate or join on it (although you are allowed to), and you get a
221	coroutine that might have executed other code already (which can be good	224	coro that might have executed other code already (which can be good
222	or bad :).	225	or bad :).
223		226
224	On the plus side, this function is faster than creating (and destroying)	227	On the plus side, this function is about twice as fast as creating (and
225	a completely new coroutine, so if you need a lot of generic coroutines in	228	destroying) a completely new coro, so if you need a lot of generic
226	quick successsion, use C<async_pool>, not C<async>.	229	coros in quick successsion, use C<async_pool>, not C<async>.
227		230
228	The code block is executed in an C<eval> context and a warning will be	231	The code block is executed in an C<eval> context and a warning will be
229	issued in case of an exception instead of terminating the program, as	232	issued in case of an exception instead of terminating the program, as
230	C<async> does. As the coroutine is being reused, stuff like C<on_destroy>	233	C<async> does. As the coro is being reused, stuff like C<on_destroy>
231	will not work in the expected way, unless you call terminate or cancel,	234	will not work in the expected way, unless you call terminate or cancel,
232	which somehow defeats the purpose of pooling (but is fine in the	235	which somehow defeats the purpose of pooling (but is fine in the
233	exceptional case).	236	exceptional case).
234		237
235	The priority will be reset to C<0> after each run, tracing will be	238	The priority will be reset to C<0> after each run, tracing will be
236	disabled, the description will be reset and the default output filehandle	239	disabled, the description will be reset and the default output filehandle
237	gets restored, so you can change all these. Otherwise the coroutine will	240	gets restored, so you can change all these. Otherwise the coro will
238	be re-used "as-is": most notably if you change other per-coroutine global	241	be re-used "as-is": most notably if you change other per-coro global
239	stuff such as C<$/> you I<must needs> to revert that change, which is most	242	stuff such as C<$/> you I<must needs> revert that change, which is most
240	simply done by using local as in: C< local $/ >.	243	simply done by using local as in: C<< local $/ >>.
241		244
242	The pool size is limited to C<8> idle coroutines (this can be adjusted by	245	The idle pool size is limited to C<8> idle coros (this can be
243	changing $Coro::POOL_SIZE), and there can be as many non-idle coros as	246	adjusted by changing $Coro::POOL_SIZE), but there can be as many non-idle
244	required.	247	coros as required.
245		248
246	If you are concerned about pooled coroutines growing a lot because a	249	If you are concerned about pooled coros growing a lot because a
247	single C<async_pool> used a lot of stackspace you can e.g. C<async_pool	250	single C<async_pool> used a lot of stackspace you can e.g. C<async_pool
248	{ terminate }> once per second or so to slowly replenish the pool. In	251	{ terminate }> once per second or so to slowly replenish the pool. In
249	addition to that, when the stacks used by a handler grows larger than 16kb	252	addition to that, when the stacks used by a handler grows larger than 32kb
250	(adjustable via $Coro::POOL_RSS) it will also be destroyed.	253	(adjustable via $Coro::POOL_RSS) it will also be destroyed.
251		254
252	=cut	255	=cut
253		256
254	our $POOL_SIZE = 8;	257	our $POOL_SIZE = 8;
255	our $POOL_RSS = 16 * 1024;	258	our $POOL_RSS = 32 * 1024;
256	our @async_pool;	259	our @async_pool;
257		260
258	sub pool_handler {	261	sub pool_handler {
259	my $cb;
260
261	while () {	262	while () {
262	eval {	263	eval {
263	while () {	264	&{&_pool_handler} while 1;
264	_pool_1 $cb;
265	&$cb;
266	_pool_2 $cb;
267	&schedule;
268	}
269	};	265	};
270		266
271	last if $@ eq "\3async_pool terminate\2\n";
272	warn $@ if $@;	267	warn $@ if $@;
273	}	268	}
274	}	269	}
275		270
276	sub async_pool(&@) {
277	# this is also inlined into the unlock_scheduler
278	my $coro = (pop @async_pool) \|\| new Coro \&pool_handler;
279
280	$coro->{_invoke} = [@_];
281	$coro->ready;
282
283	$coro
284	}
285
286	=back	271	=back
287		272
288	=head2 STATIC METHODS	273	=head1 STATIC METHODS
289		274
290	Static methods are actually functions that operate on the current coroutine.	275	Static methods are actually functions that implicitly operate on the
		276	current coro.
291		277
292	=over 4	278	=over 4
293		279
294	=item schedule	280	=item schedule
295		281
296	Calls the scheduler. The scheduler will find the next coroutine that is	282	Calls the scheduler. The scheduler will find the next coro that is
297	to be run from the ready queue and switches to it. The next coroutine	283	to be run from the ready queue and switches to it. The next coro
298	to be run is simply the one with the highest priority that is longest	284	to be run is simply the one with the highest priority that is longest
299	in its ready queue. If there is no coroutine ready, it will clal the	285	in its ready queue. If there is no coro ready, it will clal the
300	C<$Coro::idle> hook.	286	C<$Coro::idle> hook.
301		287
302	Please note that the current coroutine will I<not> be put into the ready	288	Please note that the current coro will I<not> be put into the ready
303	queue, so calling this function usually means you will never be called	289	queue, so calling this function usually means you will never be called
304	again unless something else (e.g. an event handler) calls C<< ->ready >>,	290	again unless something else (e.g. an event handler) calls C<< ->ready >>,
305	thus waking you up.	291	thus waking you up.
306		292
307	This makes C<schedule> I<the> generic method to use to block the current	293	This makes C<schedule> I<the> generic method to use to block the current
308	coroutine and wait for events: first you remember the current coroutine in	294	coro and wait for events: first you remember the current coro in
309	a variable, then arrange for some callback of yours to call C<< ->ready	295	a variable, then arrange for some callback of yours to call C<< ->ready
310	>> on that once some event happens, and last you call C<schedule> to put	296	>> on that once some event happens, and last you call C<schedule> to put
311	yourself to sleep. Note that a lot of things can wake your coroutine up,	297	yourself to sleep. Note that a lot of things can wake your coro up,
312	so you need to check wether the event indeed happened, e.g. by storing the	298	so you need to check whether the event indeed happened, e.g. by storing the
313	status in a variable.	299	status in a variable.
314		300
315	The canonical way to wait on external events is this:	301	See B<HOW TO WAIT FOR A CALLBACK>, below, for some ways to wait for callbacks.
316		302
317	{	303	=item cede
318	# remember current coroutine
319	my $current = $Coro::current;
320		304
321	# register a hypothetical event handler	305	"Cede" to other coros. This function puts the current coro into
322	on_event_invoke sub {	306	the ready queue and calls C<schedule>, which has the effect of giving
323	# wake up sleeping coroutine	307	up the current "timeslice" to other coros of the same or higher
324	$current->ready;	308	priority. Once your coro gets its turn again it will automatically be
325	undef $current;	309	resumed.
		310
		311	This function is often called C<yield> in other languages.
		312
		313	=item Coro::cede_notself
		314
		315	Works like cede, but is not exported by default and will cede to I<any>
		316	coro, regardless of priority. This is useful sometimes to ensure
		317	progress is made.
		318
		319	=item terminate [arg...]
		320
		321	Terminates the current coro with the given status values (see L<cancel>).
		322
		323	=item Coro::on_enter BLOCK, Coro::on_leave BLOCK
		324
		325	These function install enter and leave winders in the current scope. The
		326	enter block will be executed when on_enter is called and whenever the
		327	current coro is re-entered by the scheduler, while the leave block is
		328	executed whenever the current coro is blocked by the scheduler, and
		329	also when the containing scope is exited (by whatever means, be it exit,
		330	die, last etc.).
		331
		332	I<Neither invoking the scheduler, nor exceptions, are allowed within those
		333	BLOCKs>. That means: do not even think about calling C<die> without an
		334	eval, and do not even think of entering the scheduler in any way.
		335
		336	Since both BLOCKs are tied to the current scope, they will automatically
		337	be removed when the current scope exits.
		338
		339	These functions implement the same concept as C<dynamic-wind> in scheme
		340	does, and are useful when you want to localise some resource to a specific
		341	coro.
		342
		343	They slow down coro switching considerably for coros that use
		344	them (But coro switching is still reasonably fast if the handlers are
		345	fast).
		346
		347	These functions are best understood by an example: The following function
		348	will change the current timezone to "Antarctica/South_Pole", which
		349	requires a call to C<tzset>, but by using C<on_enter> and C<on_leave>,
		350	which remember/change the current timezone and restore the previous
		351	value, respectively, the timezone is only changed for the coro that
		352	installed those handlers.
		353
		354	use POSIX qw(tzset);
		355
		356	async {
		357	my $old_tz; # store outside TZ value here
		358
		359	Coro::on_enter {
		360	$old_tz = $ENV{TZ}; # remember the old value
		361
		362	$ENV{TZ} = "Antarctica/South_Pole";
		363	tzset; # enable new value
326	};	364	};
327		365
328	# call schedule until event occurred.	366	Coro::on_leave {
329	# in case we are woken up for other reasons	367	$ENV{TZ} = $old_tz;
330	# (current still defined), loop.	368	tzset; # restore old value
331	Coro::schedule while $current;	369	};
		370
		371	# at this place, the timezone is Antarctica/South_Pole,
		372	# without disturbing the TZ of any other coro.
332	}	373	};
333		374
334	=item cede	375	This can be used to localise about any resource (locale, uid, current
335		376	working directory etc.) to a block, despite the existance of other
336	"Cede" to other coroutines. This function puts the current coroutine into	377	coros.
337	the ready queue and calls C<schedule>, which has the effect of giving
338	up the current "timeslice" to other coroutines of the same or higher
339	priority. Once your coroutine gets its turn again it will automatically be
340	resumed.
341
342	This function is often called C<yield> in other languages.
343
344	=item Coro::cede_notself
345
346	Works like cede, but is not exported by default and will cede to I<any>
347	coroutine, regardless of priority. This is useful sometimes to ensure
348	progress is made.
349
350	=item terminate [arg...]
351
352	Terminates the current coroutine with the given status values (see L<cancel>).
353		378
354	=item killall	379	=item killall
355		380
356	Kills/terminates/cancels all coroutines except the currently running	381	Kills/terminates/cancels all coros except the currently running one.
357	one. This is useful after a fork, either in the child or the parent, as
358	usually only one of them should inherit the running coroutines.
359		382
360	Note that while this will try to free some of the main programs resources,	383	Note that while this will try to free some of the main interpreter
		384	resources if the calling coro isn't the main coro, but one
361	you cnanot free all of them, so if a coroutine that is not the main	385	cannot free all of them, so if a coro that is not the main coro
362	program calls this function, there will be some one-time resource leak.	386	calls this function, there will be some one-time resource leak.
363		387
364	=cut	388	=cut
365
366	sub terminate {
367	$current->cancel (@_);
368	}
369		389
370	sub killall {	390	sub killall {
371	for (Coro::State::list) {	391	for (Coro::State::list) {
372	$_->cancel	392	$_->cancel
373	if $_ != $current && UNIVERSAL::isa $_, "Coro";	393	if $_ != $current && UNIVERSAL::isa $_, "Coro";
374	}	394	}
375	}	395	}
376		396
377	=back	397	=back
378		398
379	=head2 COROUTINE METHODS	399	=head1 CORO OBJECT METHODS
380		400
381	These are the methods you can call on coroutine objects (or to create	401	These are the methods you can call on coro objects (or to create
382	them).	402	them).
383		403
384	=over 4	404	=over 4
385		405
386	=item new Coro \&sub [, @args...]	406	=item new Coro \&sub [, @args...]
387		407
388	Create a new coroutine and return it. When the sub returns, the coroutine	408	Create a new coro and return it. When the sub returns, the coro
389	automatically terminates as if C<terminate> with the returned values were	409	automatically terminates as if C<terminate> with the returned values were
390	called. To make the coroutine run you must first put it into the ready	410	called. To make the coro run you must first put it into the ready
391	queue by calling the ready method.	411	queue by calling the ready method.
392		412
393	See C<async> and C<Coro::State::new> for additional info about the	413	See C<async> and C<Coro::State::new> for additional info about the
394	coroutine environment.	414	coro environment.
395		415
396	=cut	416	=cut
397		417
398	sub _run_coro {	418	sub _coro_run {
399	terminate &{+shift};	419	terminate &{+shift};
400	}	420	}
401		421
402	sub new {
403	my $class = shift;
404
405	$class->SUPER::new (\&_run_coro, @_)
406	}
407
408	=item $success = $coroutine->ready	422	=item $success = $coro->ready
409		423
410	Put the given coroutine into the end of its ready queue (there is one	424	Put the given coro into the end of its ready queue (there is one
411	queue for each priority) and return true. If the coroutine is already in	425	queue for each priority) and return true. If the coro is already in
412	the ready queue, do nothing and return false.	426	the ready queue, do nothing and return false.
413		427
414	This ensures that the scheduler will resume this coroutine automatically	428	This ensures that the scheduler will resume this coro automatically
415	once all the coroutines of higher priority and all coroutines of the same	429	once all the coro of higher priority and all coro of the same
416	priority that were put into the ready queue earlier have been resumed.	430	priority that were put into the ready queue earlier have been resumed.
417		431
		432	=item $coro->suspend
		433
		434	Suspends the specified coro. A suspended coro works just like any other
		435	coro, except that the scheduler will not select a suspended coro for
		436	execution.
		437
		438	Suspending a coro can be useful when you want to keep the coro from
		439	running, but you don't want to destroy it, or when you want to temporarily
		440	freeze a coro (e.g. for debugging) to resume it later.
		441
		442	A scenario for the former would be to suspend all (other) coros after a
		443	fork and keep them alive, so their destructors aren't called, but new
		444	coros can be created.
		445
		446	=item $coro->resume
		447
		448	If the specified coro was suspended, it will be resumed. Note that when
		449	the coro was in the ready queue when it was suspended, it might have been
		450	unreadied by the scheduler, so an activation might have been lost.
		451
		452	To avoid this, it is best to put a suspended coro into the ready queue
		453	unconditionally, as every synchronisation mechanism must protect itself
		454	against spurious wakeups, and the one in the Coro family certainly do
		455	that.
		456
418	=item $is_ready = $coroutine->is_ready	457	=item $is_ready = $coro->is_ready
419		458
420	Return wether the coroutine is currently the ready queue or not,	459	Returns true iff the Coro object is in the ready queue. Unless the Coro
		460	object gets destroyed, it will eventually be scheduled by the scheduler.
421		461
		462	=item $is_running = $coro->is_running
		463
		464	Returns true iff the Coro object is currently running. Only one Coro object
		465	can ever be in the running state (but it currently is possible to have
		466	multiple running Coro::States).
		467
		468	=item $is_suspended = $coro->is_suspended
		469
		470	Returns true iff this Coro object has been suspended. Suspended Coros will
		471	not ever be scheduled.
		472
422	=item $coroutine->cancel (arg...)	473	=item $coro->cancel (arg...)
423		474
424	Terminates the given coroutine and makes it return the given arguments as	475	Terminates the given Coro and makes it return the given arguments as
425	status (default: the empty list). Never returns if the coroutine is the	476	status (default: the empty list). Never returns if the Coro is the
426	current coroutine.	477	current Coro.
427		478
428	=cut	479	=cut
429		480
430	sub cancel {	481	sub cancel {
431	my $self = shift;	482	my $self = shift;
432	$self->{_status} = [@_];
433		483
434	if ($current == $self) {	484	if ($current == $self) {
435	push @destroy, $self;	485	terminate @_;
436	$manager->ready;
437	&schedule while 1;
438	} else {	486	} else {
439	$self->_cancel;	487	$self->{_status} = [@_];
		488	Coro::State::cancel $self;
440	}	489	}
441	}	490	}
442		491
		492	=item $coro->schedule_to
		493
		494	Puts the current coro to sleep (like C<Coro::schedule>), but instead
		495	of continuing with the next coro from the ready queue, always switch to
		496	the given coro object (regardless of priority etc.). The readyness
		497	state of that coro isn't changed.
		498
		499	This is an advanced method for special cases - I'd love to hear about any
		500	uses for this one.
		501
		502	=item $coro->cede_to
		503
		504	Like C<schedule_to>, but puts the current coro into the ready
		505	queue. This has the effect of temporarily switching to the given
		506	coro, and continuing some time later.
		507
		508	This is an advanced method for special cases - I'd love to hear about any
		509	uses for this one.
		510
		511	=item $coro->throw ([$scalar])
		512
		513	If C<$throw> is specified and defined, it will be thrown as an exception
		514	inside the coro at the next convenient point in time. Otherwise
		515	clears the exception object.
		516
		517	Coro will check for the exception each time a schedule-like-function
		518	returns, i.e. after each C<schedule>, C<cede>, C<< Coro::Semaphore->down
		519	>>, C<< Coro::Handle->readable >> and so on. Most of these functions
		520	detect this case and return early in case an exception is pending.
		521
		522	The exception object will be thrown "as is" with the specified scalar in
		523	C<$@>, i.e. if it is a string, no line number or newline will be appended
		524	(unlike with C<die>).
		525
		526	This can be used as a softer means than C<cancel> to ask a coro to
		527	end itself, although there is no guarantee that the exception will lead to
		528	termination, and if the exception isn't caught it might well end the whole
		529	program.
		530
		531	You might also think of C<throw> as being the moral equivalent of
		532	C<kill>ing a coro with a signal (in this case, a scalar).
		533
443	=item $coroutine->join	534	=item $coro->join
444		535
445	Wait until the coroutine terminates and return any values given to the	536	Wait until the coro terminates and return any values given to the
446	C<terminate> or C<cancel> functions. C<join> can be called concurrently	537	C<terminate> or C<cancel> functions. C<join> can be called concurrently
447	from multiple coroutines, and all will be resumed and given the status	538	from multiple coro, and all will be resumed and given the status
448	return once the C<$coroutine> terminates.	539	return once the C<$coro> terminates.
449		540
450	=cut	541	=cut
451		542
452	sub join {	543	sub join {
453	my $self = shift;	544	my $self = shift;
…		…
464	}	555	}
465		556
466	wantarray ? @{$self->{_status}} : $self->{_status}[0];	557	wantarray ? @{$self->{_status}} : $self->{_status}[0];
467	}	558	}
468		559
469	=item $coroutine->on_destroy (\&cb)	560	=item $coro->on_destroy (\&cb)
470		561
471	Registers a callback that is called when this coroutine gets destroyed,	562	Registers a callback that is called when this coro gets destroyed,
472	but before it is joined. The callback gets passed the terminate arguments,	563	but before it is joined. The callback gets passed the terminate arguments,
473	if any, and I<must not> die, under any circumstances.	564	if any, and I<must not> die, under any circumstances.
474		565
475	=cut	566	=cut
476		567
…		…
478	my ($self, $cb) = @_;	569	my ($self, $cb) = @_;
479		570
480	push @{ $self->{_on_destroy} }, $cb;	571	push @{ $self->{_on_destroy} }, $cb;
481	}	572	}
482		573
483	=item $oldprio = $coroutine->prio ($newprio)	574	=item $oldprio = $coro->prio ($newprio)
484		575
485	Sets (or gets, if the argument is missing) the priority of the	576	Sets (or gets, if the argument is missing) the priority of the
486	coroutine. Higher priority coroutines get run before lower priority	577	coro. Higher priority coro get run before lower priority
487	coroutines. Priorities are small signed integers (currently -4 .. +3),	578	coro. Priorities are small signed integers (currently -4 .. +3),
488	that you can refer to using PRIO_xxx constants (use the import tag :prio	579	that you can refer to using PRIO_xxx constants (use the import tag :prio
489	to get then):	580	to get then):
490		581
491	PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN	582	PRIO_MAX > PRIO_HIGH > PRIO_NORMAL > PRIO_LOW > PRIO_IDLE > PRIO_MIN
492	3 > 1 > 0 > -1 > -3 > -4	583	3 > 1 > 0 > -1 > -3 > -4
493		584
494	# set priority to HIGH	585	# set priority to HIGH
495	current->prio(PRIO_HIGH);	586	current->prio (PRIO_HIGH);
496		587
497	The idle coroutine ($Coro::idle) always has a lower priority than any	588	The idle coro ($Coro::idle) always has a lower priority than any
498	existing coroutine.	589	existing coro.
499		590
500	Changing the priority of the current coroutine will take effect immediately,	591	Changing the priority of the current coro will take effect immediately,
501	but changing the priority of coroutines in the ready queue (but not	592	but changing the priority of coro in the ready queue (but not
502	running) will only take effect after the next schedule (of that	593	running) will only take effect after the next schedule (of that
503	coroutine). This is a bug that will be fixed in some future version.	594	coro). This is a bug that will be fixed in some future version.
504		595
505	=item $newprio = $coroutine->nice ($change)	596	=item $newprio = $coro->nice ($change)
506		597
507	Similar to C<prio>, but subtract the given value from the priority (i.e.	598	Similar to C<prio>, but subtract the given value from the priority (i.e.
508	higher values mean lower priority, just as in unix).	599	higher values mean lower priority, just as in unix).
509		600
510	=item $olddesc = $coroutine->desc ($newdesc)	601	=item $olddesc = $coro->desc ($newdesc)
511		602
512	Sets (or gets in case the argument is missing) the description for this	603	Sets (or gets in case the argument is missing) the description for this
513	coroutine. This is just a free-form string you can associate with a coroutine.	604	coro. This is just a free-form string you can associate with a
		605	coro.
514		606
515	This method simply sets the C<< $coroutine->{desc} >> member to the given string. You	607	This method simply sets the C<< $coro->{desc} >> member to the given
516	can modify this member directly if you wish.	608	string. You can modify this member directly if you wish.
517
518	=item $coroutine->throw ([$scalar])
519
520	If C<$throw> is specified and defined, it will be thrown as an exception
521	inside the coroutine at the next convinient point in time (usually after
522	it gains control at the next schedule/transfer/cede). Otherwise clears the
523	exception object.
524
525	The exception object will be thrown "as is" with the specified scalar in
526	C<$@>, i.e. if it is a string, no line number or newline will be appended
527	(unlike with C<die>).
528
529	This can be used as a softer means than C<cancel> to ask a coroutine to
530	end itself, although there is no guarentee that the exception will lead to
531	termination, and if the exception isn't caught it might well end the whole
532	program.
533		609
534	=cut	610	=cut
535		611
536	sub desc {	612	sub desc {
537	my $old = $_[0]{desc};	613	my $old = $_[0]{desc};
538	$_[0]{desc} = $_[1] if @_ > 1;	614	$_[0]{desc} = $_[1] if @_ > 1;
539	$old;	615	$old;
540	}	616	}
541		617
		618	sub transfer {
		619	require Carp;
		620	Carp::croak ("You must not call ->transfer on Coro objects. Use Coro::State objects or the ->schedule_to method. Caught");
		621	}
		622
542	=back	623	=back
543		624
544	=head2 GLOBAL FUNCTIONS	625	=head1 GLOBAL FUNCTIONS
545		626
546	=over 4	627	=over 4
547		628
548	=item Coro::nready	629	=item Coro::nready
549		630
550	Returns the number of coroutines that are currently in the ready state,	631	Returns the number of coro that are currently in the ready state,
551	i.e. that can be switched to by calling C<schedule> directory or	632	i.e. that can be switched to by calling C<schedule> directory or
552	indirectly. The value C<0> means that the only runnable coroutine is the	633	indirectly. The value C<0> means that the only runnable coro is the
553	currently running one, so C<cede> would have no effect, and C<schedule>	634	currently running one, so C<cede> would have no effect, and C<schedule>
554	would cause a deadlock unless there is an idle handler that wakes up some	635	would cause a deadlock unless there is an idle handler that wakes up some
555	coroutines.	636	coro.
556		637
557	=item my $guard = Coro::guard { ... }	638	=item my $guard = Coro::guard { ... }
558		639
559	This creates and returns a guard object. Nothing happens until the object	640	This function still exists, but is deprecated. Please use the
560	gets destroyed, in which case the codeblock given as argument will be	641	C<Guard::guard> function instead.
561	executed. This is useful to free locks or other resources in case of a
562	runtime error or when the coroutine gets canceled, as in both cases the
563	guard block will be executed. The guard object supports only one method,
564	C<< ->cancel >>, which will keep the codeblock from being executed.
565		642
566	Example: set some flag and clear it again when the coroutine gets canceled
567	or the function returns:
568
569	sub do_something {
570	my $guard = Coro::guard { $busy = 0 };
571	$busy = 1;
572
573	# do something that requires $busy to be true
574	}
575
576	=cut	643	=cut
577		644
578	sub guard(&) {	645	BEGIN { *guard = \&Guard::guard }
579	bless \(my $cb = $_[0]), "Coro::guard"
580	}
581
582	sub Coro::guard::cancel {
583	${$_[0]} = sub { };
584	}
585
586	sub Coro::guard::DESTROY {
587	${$_[0]}->();
588	}
589
590		646
591	=item unblock_sub { ... }	647	=item unblock_sub { ... }
592		648
593	This utility function takes a BLOCK or code reference and "unblocks" it,	649	This utility function takes a BLOCK or code reference and "unblocks" it,
594	returning a new coderef. Unblocking means that calling the new coderef	650	returning a new coderef. Unblocking means that calling the new coderef
595	will return immediately without blocking, returning nothing, while the	651	will return immediately without blocking, returning nothing, while the
596	original code ref will be called (with parameters) from within another	652	original code ref will be called (with parameters) from within another
597	coroutine.	653	coro.
598		654
599	The reason this function exists is that many event libraries (such as the	655	The reason this function exists is that many event libraries (such as the
600	venerable L<Event\|Event> module) are not coroutine-safe (a weaker form	656	venerable L<Event\|Event> module) are not thread-safe (a weaker form
601	of thread-safety). This means you must not block within event callbacks,	657	of reentrancy). This means you must not block within event callbacks,
602	otherwise you might suffer from crashes or worse. The only event library	658	otherwise you might suffer from crashes or worse. The only event library
603	currently known that is safe to use without C<unblock_sub> is L<EV>.	659	currently known that is safe to use without C<unblock_sub> is L<EV>.
604		660
605	This function allows your callbacks to block by executing them in another	661	This function allows your callbacks to block by executing them in another
606	coroutine where it is safe to block. One example where blocking is handy	662	coro where it is safe to block. One example where blocking is handy
607	is when you use the L<Coro::AIO\|Coro::AIO> functions to save results to	663	is when you use the L<Coro::AIO\|Coro::AIO> functions to save results to
608	disk, for example.	664	disk, for example.
609		665
610	In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when	666	In short: simply use C<unblock_sub { ... }> instead of C<sub { ... }> when
611	creating event callbacks that want to block.	667	creating event callbacks that want to block.
612		668
613	If your handler does not plan to block (e.g. simply sends a message to	669	If your handler does not plan to block (e.g. simply sends a message to
614	another coroutine, or puts some other coroutine into the ready queue),	670	another coro, or puts some other coro into the ready queue), there is
615	there is no reason to use C<unblock_sub>.	671	no reason to use C<unblock_sub>.
616		672
617	Note that you also need to use C<unblock_sub> for any other callbacks that	673	Note that you also need to use C<unblock_sub> for any other callbacks that
618	are indirectly executed by any C-based event loop. For example, when you	674	are indirectly executed by any C-based event loop. For example, when you
619	use a module that uses L<AnyEvent> (and you use L<Coro::AnyEvent>) and it	675	use a module that uses L<AnyEvent> (and you use L<Coro::AnyEvent>) and it
620	provides callbacks that are the result of some event callback, then you	676	provides callbacks that are the result of some event callback, then you
…		…
629	# return immediately and can be reused) and because we cannot cede	685	# return immediately and can be reused) and because we cannot cede
630	# inside an event callback.	686	# inside an event callback.
631	our $unblock_scheduler = new Coro sub {	687	our $unblock_scheduler = new Coro sub {
632	while () {	688	while () {
633	while (my $cb = pop @unblock_queue) {	689	while (my $cb = pop @unblock_queue) {
634	# this is an inlined copy of async_pool	690	&async_pool (@$cb);
635	my $coro = (pop @async_pool) \|\| new Coro \&pool_handler;
636		691
637	$coro->{_invoke} = $cb;
638	$coro->ready;
639	cede; # for short-lived callbacks, this reduces pressure on the coro pool	692	# for short-lived callbacks, this reduces pressure on the coro pool
		693	# as the chance is very high that the async_poll coro will be back
		694	# in the idle state when cede returns
		695	cede;
640	}	696	}
641	schedule; # sleep well	697	schedule; # sleep well
642	}	698	}
643	};	699	};
644	$unblock_scheduler->desc ("[unblock_sub scheduler]");	700	$unblock_scheduler->{desc} = "[unblock_sub scheduler]";
645		701
646	sub unblock_sub(&) {	702	sub unblock_sub(&) {
647	my $cb = shift;	703	my $cb = shift;
648		704
649	sub {	705	sub {
650	unshift @unblock_queue, [$cb, @_];	706	unshift @unblock_queue, [$cb, @_];
651	$unblock_scheduler->ready;	707	$unblock_scheduler->ready;
652	}	708	}
653	}	709	}
654		710
		711	=item $cb = Coro::rouse_cb
		712
		713	Create and return a "rouse callback". That's a code reference that,
		714	when called, will remember a copy of its arguments and notify the owner
		715	coro of the callback.
		716
		717	See the next function.
		718
		719	=item @args = Coro::rouse_wait [$cb]
		720
		721	Wait for the specified rouse callback (or the last one that was created in
		722	this coro).
		723
		724	As soon as the callback is invoked (or when the callback was invoked
		725	before C<rouse_wait>), it will return the arguments originally passed to
		726	the rouse callback.
		727
		728	See the section B<HOW TO WAIT FOR A CALLBACK> for an actual usage example.
		729
655	=back	730	=back
656		731
657	=cut	732	=cut
658		733
659	1;	734	1;
660		735
		736	=head1 HOW TO WAIT FOR A CALLBACK
		737
		738	It is very common for a coro to wait for some callback to be
		739	called. This occurs naturally when you use coro in an otherwise
		740	event-based program, or when you use event-based libraries.
		741
		742	These typically register a callback for some event, and call that callback
		743	when the event occured. In a coro, however, you typically want to
		744	just wait for the event, simplyifying things.
		745
		746	For example C<< AnyEvent->child >> registers a callback to be called when
		747	a specific child has exited:
		748
		749	my $child_watcher = AnyEvent->child (pid => $pid, cb => sub { ... });
		750
		751	But from within a coro, you often just want to write this:
		752
		753	my $status = wait_for_child $pid;
		754
		755	Coro offers two functions specifically designed to make this easy,
		756	C<Coro::rouse_cb> and C<Coro::rouse_wait>.
		757
		758	The first function, C<rouse_cb>, generates and returns a callback that,
		759	when invoked, will save its arguments and notify the coro that
		760	created the callback.
		761
		762	The second function, C<rouse_wait>, waits for the callback to be called
		763	(by calling C<schedule> to go to sleep) and returns the arguments
		764	originally passed to the callback.
		765
		766	Using these functions, it becomes easy to write the C<wait_for_child>
		767	function mentioned above:
		768
		769	sub wait_for_child($) {
		770	my ($pid) = @_;
		771
		772	my $watcher = AnyEvent->child (pid => $pid, cb => Coro::rouse_cb);
		773
		774	my ($rpid, $rstatus) = Coro::rouse_wait;
		775	$rstatus
		776	}
		777
		778	In the case where C<rouse_cb> and C<rouse_wait> are not flexible enough,
		779	you can roll your own, using C<schedule>:
		780
		781	sub wait_for_child($) {
		782	my ($pid) = @_;
		783
		784	# store the current coro in $current,
		785	# and provide result variables for the closure passed to ->child
		786	my $current = $Coro::current;
		787	my ($done, $rstatus);
		788
		789	# pass a closure to ->child
		790	my $watcher = AnyEvent->child (pid => $pid, cb => sub {
		791	$rstatus = $_[1]; # remember rstatus
		792	$done = 1; # mark $rstatus as valud
		793	});
		794
		795	# wait until the closure has been called
		796	schedule while !$done;
		797
		798	$rstatus
		799	}
		800
		801
661	=head1 BUGS/LIMITATIONS	802	=head1 BUGS/LIMITATIONS
662		803
		804	=over 4
		805
		806	=item fork with pthread backend
		807
		808	When Coro is compiled using the pthread backend (which isn't recommended
		809	but required on many BSDs as their libcs are completely broken), then
		810	coro will not survive a fork. There is no known workaround except to
		811	fix your libc and use a saner backend.
		812
		813	=item perl process emulation ("threads")
		814
663	This module is not perl-pseudo-thread-safe. You should only ever use this	815	This module is not perl-pseudo-thread-safe. You should only ever use this
664	module from the same thread (this requirement might be removed in the	816	module from the first thread (this requirement might be removed in the
665	future to allow per-thread schedulers, but Coro::State does not yet allow	817	future to allow per-thread schedulers, but Coro::State does not yet allow
666	this). I recommend disabling thread support and using processes, as this	818	this). I recommend disabling thread support and using processes, as having
667	is much faster and uses less memory.	819	the windows process emulation enabled under unix roughly halves perl
		820	performance, even when not used.
		821
		822	=item coro switching is not signal safe
		823
		824	You must not switch to another coro from within a signal handler
		825	(only relevant with %SIG - most event libraries provide safe signals).
		826
		827	That means you I<MUST NOT> call any function that might "block" the
		828	current coro - C<cede>, C<schedule> C<< Coro::Semaphore->down >> or
		829	anything that calls those. Everything else, including calling C<ready>,
		830	works.
		831
		832	=back
		833
668		834
669	=head1 SEE ALSO	835	=head1 SEE ALSO
670		836
671	Event-Loop integration: L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>.	837	Event-Loop integration: L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>.
672		838
673	Debugging: L<Coro::Debug>.	839	Debugging: L<Coro::Debug>.
674		840
675	Support/Utility: L<Coro::Specific>, L<Coro::Util>.	841	Support/Utility: L<Coro::Specific>, L<Coro::Util>.
676		842
677	Locking/IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>, L<Coro::SemaphoreSet>, L<Coro::RWLock>.	843	Locking and IPC: L<Coro::Signal>, L<Coro::Channel>, L<Coro::Semaphore>,
		844	L<Coro::SemaphoreSet>, L<Coro::RWLock>.
678		845
679	IO/Timers: L<Coro::Timer>, L<Coro::Handle>, L<Coro::Socket>, L<Coro::AIO>.	846	I/O and Timers: L<Coro::Timer>, L<Coro::Handle>, L<Coro::Socket>, L<Coro::AIO>.
680		847
681	Compatibility: L<Coro::LWP>, L<Coro::BDB>, L<Coro::Storable>, L<Coro::Select>.	848	Compatibility with other modules: L<Coro::LWP> (but see also L<AnyEvent::HTTP> for
		849	a better-working alternative), L<Coro::BDB>, L<Coro::Storable>,
		850	L<Coro::Select>.
682		851
683	XS API: L<Coro::MakeMaker>.	852	XS API: L<Coro::MakeMaker>.
684		853
685	Low level Configuration, Coroutine Environment: L<Coro::State>.	854	Low level Configuration, Thread Environment, Continuations: L<Coro::State>.
686		855
687	=head1 AUTHOR	856	=head1 AUTHOR
688		857
689	Marc Lehmann <schmorp@schmorp.de>	858	Marc Lehmann <schmorp@schmorp.de>
690	http://home.schmorp.de/	859	http://home.schmorp.de/

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Comparing Coro/Coro.pm (file contents): Revision 1.186 by root, Sun May 25 01:32:36 2008 UTC vs. Revision 1.252 by root, Thu Apr 16 20:07:21 2009 UTC

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Comparing Coro/Coro.pm (file contents):
Revision 1.186 by root, Sun May 25 01:32:36 2008 UTC vs.
Revision 1.252 by root, Thu Apr 16 20:07:21 2009 UTC